It may be possible to locate or track a person associated with a specific device indoors via a radio frequency (RF)-based tracking. Tracking people indoors on the basis of variations in the Earth's indoor magnetic field has also been proposed. This type of location discovery typically applies magnetic field strengths measured by a magnetometer carried by the person. The measured strength is compared to an existing indoor magnetic field map to derive the location of the magnetometer, and thus, the person. However, the above techniques for detecting persons' movements require knowledge of an indoor map, which may not be initially available.